As this type of anti-vibration device, there is conventionally known an anti-vibration device including a tubular first attachment member connected to either a vibration generating section or a vibration receiving section; a second attachment member connected to the other of the vibration generating section and the vibration receiving section; a first rubber elastic body elastically interconnecting the first and second attachment members; a partition member partitioning the inside of the first attachment member into a main liquid chamber and a sub liquid chamber, and an orifice passage provided between the outer peripheral surface of the partition member and the inner peripheral surface of the first attachment member so as to communicate the main liquid chamber and the sub liquid chamber, in which the liquid is enclosed in the main liquid chamber and the sub liquid chamber, and the main liquid chamber has a first partition wall and has liquid enclosed therein, an inner volume of the main liquid chamber changes due to deformation of the first rubber elastic body, a part of the first partition wall is formed of the first rubber elastic body, the sub liquid chamber has a second partition wall and has liquid enclosed therein, at least a part of the second partition wall is adapted to be deformable.
In this anti-vibration device, conventionally, the main liquid chamber may have a negative pressure, for example, when vibration is input in an opposite direction due to the rebound or the like of the first rubber elastic body after a large vibration (load) is input due to irregularity or the like of a road surface and the fluid pressure of the main liquid chamber rises abruptly. At this time, cavitation by which a number of bubbles are generated in the liquid within the main liquid chamber occurs. Thereafter, when the bubbles disappear out of the liquid as the fluid pressure within the main liquid chamber rises, shock waves are generated, and these shock waves propagate to metallic materials, such as the first attachment member, whereby abnormal noise is generated.
As a means for preventing generation of such abnormal noise, as shown in the following Patent Document 1, there is known a configuration in which a communication hole which allows a main liquid chamber and a sub liquid chamber to communicate with each other is formed in a partition member separately from an orifice passage, a valve is provided in this communication hole, and when the fluid pressure of the main liquid chamber will become a negative pressure after the fluid pressure has risen abruptly, the valve is opened to short-circuit the main liquid chamber and the sub liquid chamber to inhibit the fluid pressure of the main liquid chamber from falling in advance, thereby preventing the cavitation from occurring.
[Patent Document 1] Japanese Unexamined Patent Application, First Publication No. 2003-148548.